The benefits of regular aerobic exercise have been well established and accepted. However, due to time constraints, inclement weather, and other reasons, many people are prevented from indulging in activities such as walking, jogging, running, and swimming. In response, a variety of exercise equipment have been developed for aerobic activity. It is generally desirable to exercise a large number of different muscles over a significantly large range of motion so as to provide for even physical development, to maximize muscle length and flexibility, and to achieve optimum levels of aerobic exercise. A further advantageous characteristic of exercise equipment, is the ability to provide smooth and natural motion, thus avoiding significant jarring and straining that can damage both muscles and joints.
While various exercise systems are known in the prior art, these systems suffer from a variety of shortcomings that limit their benefits and/or include unnecessary risks and undesirable features. For example, stationary bicycles are a popular exercise system in the prior art, however this machine employs a sitting position which utilizes only a small number of muscles, throughout a fairly limited range of motion. Cross-country skiing devices are also utilized by many people to simulate the gliding motion of cross-country skiing. While this device exercises more muscles than a stationary bicycle, the substantially flat shuffling foot motion provided thereby, limits the range of motion of some of the muscles being exercised. Another type of exercise device simulates stair climbing. These devices also exercise more muscles than do stationary bicycles, however, the rather limited range of up-and-down motion utilized does not exercise the user's leg muscles through a large range of motion. Treadmills are still a further type of exercise device in the prior art, and allow natural walking or jogging motions in a relatively limited area. A drawback of the treadmill, however, is that significant jarring of the hip, knee, ankle and other joints of the body may occur through use of this device.
A further limitation of a majority of exercise systems in the prior art, is that the systems produce an equipment-induced, reciprocal coordinated motion between a user's legs. This motion can result in detrimental effects on a user's balance and muscle coordination due to the continued reliance on the forced coordinated motion produced by some prior art exercise equipment, as opposed to the natural independent motion that occurs in activities such as running, walking, etc. There is a continuing need for an exercise device that provides for smooth natural action, exercises a relatively large number of muscles through a large range of motion, and allows for independent bi-pedal motion instead of forced reciprocal coordinated motion.